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Exposing jest.runToFrame() from sinon/fake_timers #14598

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merged 13 commits into from
Oct 5, 2023

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alexreardon
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@alexreardon alexreardon commented Oct 3, 2023

Closes #14593

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@@ -989,6 +989,16 @@ This function is not available when using legacy fake timers implementation.

:::

### `jest.runToFrame()`
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Should I add these changes to 29.7 docs or just the base docs like I have now?

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Just base 👍

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alexreardon commented Oct 3, 2023

Update: never mind, I found where this check should happen (jest runtime). I have updated the PR


@SimenB you mentioned that

It should also throw when using legacy timers

I can add that, but I did not see any other cases of that so I have not for now. I can add that if you still want it

@alexreardon alexreardon changed the title Exposing jest.runToFrame() from sinon/fake_timers in @jest/fake-timers Exposing jest.runToFrame() from sinon/fake_timers Oct 4, 2023
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It looks like the build failures are caused by unrelated issues

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Perfect, thanks!

In addition to my API question, could you add a changelog entry? 🙂

@@ -989,6 +989,16 @@ This function is not available when using legacy fake timers implementation.

:::

### `jest.runToFrame()`
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Should we call it runToNextFrame? runToFrame sounds to me like it'd take which frame (or a number of frames) as an argument

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I just mirrored the sinon api without too much thought 😊

runToNextFrame() feels nice and fits with runOnlyPendingTimers().
Another idea: advanceTimersToNextFrame() - fits in with `advanceTimersToNextTimer()

Which do you lean towards? (Or something else?)

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yeah, advanceTimersToNextFrame sounds perfect to align with existing functions 👍

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Cc @SimenB

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hmm? I believe I answered the question? 😅

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Sorry, for some reason I didn't see your reply

docs/TimerMocks.md Outdated Show resolved Hide resolved
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SimenB commented Oct 4, 2023

It looks like the build failures are caused by unrelated issues

Yeah, the windows tests has a bit of flake, unfortunately

@@ -349,6 +349,14 @@ export interface Jest {
* It is recommended to use `jest.mock()` instead. The `jest.mock()` API's second
* argument is a module factory instead of the expected exported module object.
*/
/**
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The above TSDoc belongs to 'setMock'. Would be good to move it down (;

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Thanks! Fixed

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Hi @SimenB,

I think I have addressed all the open feedback. Please take a look and let me know what you think


In applications, often you want to schedule work inside of an animation frame (with `requestAnimationFrame`). We expose a convenience method `jest.advanceTimersToNextFrame()` to advance all timers enough milliseconds to execute all actively scheduled animation frames.

For mock timing purposes, animation frames are executed every `16ms` (mapping to roughly `60` frames per second) after the clock starts. When you schedule a callback in an animation frame (with `requestAnimationFrame(callback)`), the `callback` will be called when the clock has advanced `16ms`. `jest.advanceTimersToNextFrame()` will advance the clock just enough to get to the next `16ms` increment. If the clock has already advanced `6ms` since a animation frame `callback` was scheduled, then the clock will be advanced by `10ms`.
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A added some more detail here to hopefully make things clearer for consumers

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perfect, thanks!

@SimenB SimenB merged commit 00ef0ed into jestjs:main Oct 5, 2023
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Here is a workaround for anybody who needs it before jest.advanceTimersToNextFrame() lands:

// ensure you are using "modern" fake timers
// 1. before doing anything, grab the start time `setStartSystemTime()`
// 2. step through frames by using `advanceTimersToNextFrame()`

let startTime: number | null = null;

/** Record the initial (mocked) system start time 
 * 
 * This is no longer needed once `jest.advanceTimersToNextFrame()` is available
 * https://github.com/jestjs/jest/pull/14598
*/
export function setStartSystemTime() {
  startTime = Date.now();
}

/** Step forward a single animation frame
 * 
 * This is no longer needed once `jest.advanceTimersToNextFrame()` is available
 * https://github.com/jestjs/jest/pull/14598
 */
export function advanceTimersToNextFrame() {
  if(startTime == null) {
     throw new Error('Must call `setStartSystemTime` before using `advanceTimersToNextFrame()`');
  }

  // Stealing logic from sinon fake timers
  // https://github.com/sinonjs/fake-timers/blob/fc312b9ce96a4ea2c7e60bb0cccd2c604b75cdbd/src/fake-timers-src.js#L1102-L1105
  const timePassedInFrame = (Date.now() - startTime) % 16;
  const timeToNextFrame = 16 - timePassedInFrame;
  jest.advanceTimersByTime(timeToNextFrame);
}

nicojs pushed a commit to nicojs/jest that referenced this pull request Oct 13, 2023
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SimenB commented Oct 30, 2023

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This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
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@github-actions github-actions bot locked as resolved and limited conversation to collaborators Nov 30, 2023
@alexreardon alexreardon deleted the exposing-run-to-frame branch August 15, 2024 12:04
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[Feature]: Please expose runToFrame() from sinon/fake_timers in @jest/fake-timers
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